Pumps

ABSTRACT

A PERISTALTIC PUMP COMPRISES A FLEXIBLE TUBE IN THE FORM OF A COIL HAVING A SINGLE COMPLETE CONVOLUTION ENCIRCLED BY A FIXED SUPPORT, AND A MEMBER DISPOSED TO COMPRESS A PART OF THE TUBE AGAINST SAID SUPPORT AND ROTATABLE ABOUT THE CENTRAL AXIS OF THE COIL. THE LENGTH OF THE MEMBER IN THE DIRECTION OF SAID AXIS IS SUCH THAT THE MEMBER SUCCESSIVELY COMPRESSES ALL PARTS OF THE CONVOLUTION OF THE TUBE DURING EACH ROTATION OF THE MEMBER. THE INTERNAL SURFACE OF THE SUPPORT IS CONICAL, AND THE MEMBER IS CONICAL OR INCLINED SO THAT THE PRESSURE OF THE MEMBER ON THE TUBE MAY BE ADJUSTED BY AXIAL MOVEMENT OF THE MEMBER.

F. [LES PUMPS July 4, 1972 2 Sheets-Sheet 1 Filed Sept. 1 1970 July 4,1972 2 Sheets-Sheet 2 Filed Sept. 1, 1970 United States Patent 3,674,383PUMPS Frank Hes, Loscombe, Four Lanes, Redruth, Cornwall, England FiledSept. 1, 1970, Ser. No. 68,749 Claims priority, application GreatBritain, Sept. 5, 1969, 44,040/69; Apr. 16, 1970, 18,296/70 Int. Cl.F04b 43/08, 43/12, 45/06 US. Cl. 417-476 4 Claims ABSTRACT OF THEDISCLOSURE A peristaltic pump comprises a flexible tube in the form of acoil having a single complete convolution encircled by a fixed support,and a member disposed to compress a part of the tube against saidsupport and rotatable about the central axis of the coil. The length ofthe member in the direction of said axis is such that the membersuccessively compresses all parts of the convolution of the tube duringeach rotation of the member. The internal surface of the support isconical, and the member is conical or inclined so that the pressure ofthe member on the tube may be adjusted by axial movement of the member.

The invention relates to pumps of the kind which induce a flow of fluidalong a flexible walled tube by repeatedly contracting the tube at apoint and moving the contraction along the tube for a distance so as toforce a body of fluid along the tube in front of the contraction. Such apump will hereinafter be referred to as a peristaltic pump.

Accordingly the invention comprises a peristaltic pump of the kindreferred to wherein the flexible tube is in the form of a coil having atleast one complete convolution encircled by a fixed support and a memberdisposed to compress a part of the tube against said support androtatable about the central axis of the coil, the length of said memberin the direction of said axis being such that the member successivelycompresses all parts of at least one complete convolution of the tubeduring each rotation of the member.

Preferably the coil comprises only a single complete convolution.

It is also preferred that said fixed support comprises a tubularstructure encircling the coil or a part thereof.

Preferably the distance of said member from the inner surface of thesupport is adjustable. For example the inner surface of the support,engaging the tube, may be inclined to the central axis of the coil andthe surface of the member may be similarly inclined and be longer thanthe axial length of said convolution, so that movement of said member inthe direction of the central axis of the coil changes the distance ofthe surface of the member from the inner surface of the support, thuschanging the degree of compression of the flexible tube.

Where the fixed support is a tubular structure its inner surface may bein the form of a frustrum of a cone. The member may be a roller in theform of a frustrum of a cone with its axis lying parallel to the centralaxis of the coil.

Alternatively the member may be a cylindrical roller having its axisinclined to the central axis of the coil and parallel to the innersurface of the support.

The coil is preferably capable of being fixed relatively to said tubularstructure. For this purpose the tubular structure may be formed in twoparts adapted to be secured together, one part including locating meansfor one end of the coil and the other part of the tubular structureincluding locating means for the other end of the coil.

Patented July 4, 1972 The locating means may comprise a slot formed ineach part of said tubular structure and blocks capable of sliding ineach said slot and of engaging against said tube, to hold it when itextends through said slot, by the clamping of the two parts of saidtubular structure together.

The following is a more detailed description of various embodiments ofthe invention, by way of example, reference being made to theaccompanying drawings in which:

FIG. 1 is a plan view of a peristaltic pump, one end of the pump beingshown in section;

FIG. 2 is an end view of FIG. 1;

FIG. 3 is a side view of the pump;

FIG. 4 is a detailed view of a part of FIG. 3;

FIG. 5 is a diagrammatic perpsective view of a modified form of pump;and

FIG. 6 is a perspective view showing a fragment of a modified form oftube for use in the pump.

The pump comprises a driving portion 10 and a pump portion 11, bothmounted on a base 12. The driving portion 10 comprises an electric motorv13 mounted on the base 12 and capable of sliding movement relatively tothe base 12 in the direction of its axis so that its position relativelyto the pump portion 11 may be adjusted. The drive shaft 14 of theelectric motor 13 carries a disc 15, as best shown in FIGS. 1 and 2.Towards the outer periphery of the disc is mounted a roller spindle 16(as best shown in FIG. 2) on which is mounted a frusto-conical roller 17carried on two ball races, one of which is shown at 18, so as to berotatable on the spindle 16. The roller 17 is circular in cross-sectionand tapers away from the surface of the disc 15.

The pump housing 11 comprises a pair of blocks 19, 20 which are offrusto-conical internal cross-section having tapered surfaces 21 and 22respectively. The angle of taper of the surfaces 21, 22 is substantiallythe same as the angle of taper of the roller 17. The blocks 19, 20 arealigned axially with the motor 13 so that their internal surfaces taperaway from the disc 15. Each block is provided with a slot 23 (see FIGS.3 and 4) on one side thereof, so that when the two blocks 19, 20 areapart, one part of a flexible tube 24 may be inserted into the slot ofone block 19, and another part of the flexible tube 24 inserted into theslot in the other block 20 Locking blocks 25, which are formed withcurved end surfaces, are then fitted into the slots and, as the blocksare faced together and clamped together by wing nuts 26, the curved endsurfaces of the locking blocks 25 engage the flexible tube 24 to hold itfirmly in position at the points where it passes through the slots 23.Within the pump assembly 11 the flexible tube 24 is formed into a coilhaving a single convolution which extends around the tapered surfaces21, 22 of the two blocks 19, 20.

The roller 17 is so positioned on the disc 15 that it is in contact withthe flexible tube 24 as it rotates with the disc 15.

The action of the pump is as follows. The flexible tube 24 forms part ofa delivery conduit containing a fluid which it is desired to pump. Forexample, the pump may be used for pumping blood since the blood does notcome into contact with any of the moving parts of the pump but onlycontacts the tube 24 which may be easily sterilised. The electric motor13 is started and the disc 15 is rotated by the drive shaft 14, sorotating the spindle 16 on which is mounted the roller 17. Due to theaction of the bearings 18 the roller may rotate relatively to thespindle 16 as the disc 15 rotates. As the disc 15 rotates the roller 17compresses the surface of the coil of flexible tubing 24 causing a waveof high pressure to move in front of the roller 17 and a wave of lowpressure to follow the roller 17. As the roller 17 reaches the end ofthe convolution of flexible tubing 24 which lies closest to the disc itcomes again into contact with the beginning of the convolution which isfurthest away from the disc 15. Thus the fluid being pumped is alwaysprevented by the roller from passing back round the convolution and iscontinually forced through the tube.

The fact that the pump housing 11 is formed in two parts 19, enables atube to be used which is a part of a continuous circuit, without theneed for disconnecting either of the ends of the tube.

The rate of fiow of liquid through the tube 24 may be varied in one oftwo ways. Firstly, the motor 13 may be adjusted relatively to the base12 in the direction of its axis to move the roller 17 in and out of thepump housing. The movement of the motor 13 towards or away from the pumphousing may be achieved by means of a screw thread arrangement which isconnected to the motor 13 and is mounted for movement relatively to thebase 12. In such an arrangement the motor 13 is slidably mounted on thebase 12 and rotation of the screw thread by means of a hand wheel or thelike moves the motor 13 either forwards or away from the pump housing.If the roller 17 is withdrawn from the housing, the action of thecomplementary tapered surfaces of the roller 17 and the blocks 19 and 20means that the surface of the roller 17 moves further away from thesurfaces 21, 22 and consequently exerts less pressure on the surface ofthe flexible tube 24. Thus the magnitude of the pressure wave decreasesand consequently the rate of pumping also decreases. Movement of theelectric motor 13 towards the pump housing 11 closes the gap between thesurfaces and increases the pressure exerted by the roller 17 on theflexible tube 24, so increasing the rate of pumping.

The second method of varying the rate of pumping is to vary the speed ofrotation of the motor 13. This method is not capable of achieving suchfine variations in the rate of flow as the first method.

It will be appreciated that as long as at least one complete convolutionof flexible tubing is provided within the block assembly 11 the lengthof the coil may be varied at will, the only condition being that theroller must be in contact with such a coil along the whole length of atleast one convolution. It will also be appreciated that a number ofrollers may be provided around the disc 15, which will result in acorresponding increase in the rate of pumping.

In the modified form of pump shown in FIG. 5, the tube 24, at either endof the convolution, is fixed in position by the tubular structure. Inorder to fix the tube in its coiled position in the convolution, a tape31 made of nylon, glass fibre or other suitable materials, is placedround the tube at the top point of the convolution. The two ends areclamped between the pump housing blocks 19 and 20, as shown in FIG. 5.Other tapes may be similarly fixed at other points in the coil if sorequired. To ensure a constant length for the tape, one end is securedto the pump housing block 20, by a retaining stud 32 which acts as themate unit for a press fastener (not shown) on the opposite end of thetape.

Alternatively, as shown in FIG. 6, the tube could be manufactured inplastics with a lug 33 moulded in, which could be clamped between thepump housing blocks.

A further modification employed in the construction of FIG. 5 is thatthe locking blocks 25 are integral with the blocks 19 and 20 instead ofbeing separately formed as in the arrangement of FIGS. 1 to 4.

Also in FIG. 5, the roller 17, instead of being tapered is cylindricaland the axis of rotation of the roller is inclined inwardly slightlytowards the central axis of the coil so as to be parallel to the taperedinternal surfaces of the blocks 19 and 20. It will be appreciated thatin this arrangement also, axial adjustment of the motor 10 will bringthe roller 17 closer to or further from the tapered surfaces of theblocks 19 and 20' and will thus vary the pumping rate.

If two pumps are run-coupled together so that one motor and one driveshaft serve both, and the pumps are run out of phase, not only can thepumps be operated at identical speeds but any slight pulse in the onepump can be cancelled out by the pulse in the other.

I claim:

1. A peristaltic pump comprising a flexible tube in the form of a coilhaving at least one complete convolution; a fixed support encircling theconvolution of the tube; a member disposed to compress a part of thetube against said support; and means to rotate the member about thecentral axis of the coil, a length of said member in the direction ofsaid axis being such that the member successively compresses all partsof at least one complete convolution of the tube during each rotation ofthe member; the inner surface of the support, engaging the tube, beinginclined to the central axis of the coil and the surface of the memberbeing similarly inclined and longer than the axial length of saidconvolution, the distance of said member from said inner surface of saidsupport being adjustable so that movement of said member in thedirection of the central axis of the convolution changes the distance ofthe surface of the memher from the inner surface of the support tochange the degree of compression of the flexible tube.

2. A pump according to claim 1 wherein the fixed support is a tubularstructure the inner surface of which is in the form of a frustum of acone.

3. A pump according to claim 1 wherein the member is a roller in theform of a frustum of a cone with its axis lying parallel to the centralaxis of the convolution.

4. A pump according to claim 1 wherein the member is a cylindricalroller having its axis inclined to the central axis of the convolutionand parallel to the inner surface of the support.

References Cited UNITED STATES PATENTS 2,679,807 6/1954 Bruckmann 4l7476X 2,930,326 3/1960 Simer et al. 417-477 X 2,752,852 7/1956 Offutt 4l74743,427,986 2/1969 Cornell 417-474 3,584,983 6/1971 Hindman et a1 417-476CARLTON R. CROYLE, Primary Examiner R. E. GLUCK, Assistant Examiner US.Cl. X.R. 418-45; 92-l3.2

